In April I wrote about how I use the `platform_define` feature of [rebar](https://github.com/rebar/rebar) to make deprecated types work without removing `warnings_as_errors`. I have switched to [erlang.mk](https://github.com/ninenines/erlang.mk) since then, but needed a similar feature for [one of my libraries](https://github.com/nifoc/noesis).
Since erlang.mk only uses [make](http://en.wikipedia.org/wiki/Make_(software)), adding support for a `platform_define`-like feature is very straightforward.
The first variable (`otp_release`) will contain the OTP version (e.g. `17`). The second variable (`otp_17plus`) will be either `0` or `1`, depending on wether or not `otp_release` matches a regular expression. The regular expression checks if `otp_release` is just a number (e.g. `17`) or not (e.g. `R16B03-1`).
That's enough to conditionally add options to `erlc`.